Chicago train crash mystery

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48 people were injured; 33 taken to hospitals, CNN affiliate WLS reported

The crash affected Chicago's Monday morning commute

A Chicago commuter train that was parked in a service yard somehow moved onto a rail line and smashed into an oncoming train early Monday, injuring dozens of people.

How it happened is a mystery.

"I don't know the last time, if ever, that this has happened" on the Chicago Transit Authority system, spokesman Brian Steele said.

There are "more questions than answers" about the incident in Forest Park, Illinois, he said.

At least 48 people were injured; 33 of them were transported to hospitals, Forest Park Mayor Anthony Calderone told CNN affiliate WLS. They are believed to have minor injuries.

It was not immediately clear how many passengers were aboard the train.

Photos: Chicago train crash 5 photos

Photos: Chicago train crash5 photos

Chicago train crash – A Chicago commuter train that was parked in a service yard moved onto a rail line and smashed into an oncoming train early Monday, September 30. At least 48 people were injured; 33 of them were transported to hospitals, Forest Park Mayor Anthony Calderone told CNN affiliate WLS. They are believed to have minor injuries.

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Photos: Chicago train crash5 photos

Chicago train crash – Emergency personnel investigate the scene on September 30 after a Chicago Transit Authority train ran head-on into another train that was stopped at a Blue Line station in Forest Park, Illinois.

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Photos: Chicago train crash5 photos

Chicago train crash – An injured rider is transported by emergency workers after the head-on collision on September 30.

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Photos: Chicago train crash5 photos

Chicago train crash – An injured rider is transported after the crash. Authorities are looking at video feeds from the platforms and from some rail cars.

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Photos: Chicago train crash5 photos

Chicago train crash – Emergency personnel investigate the scene where a CTA train ran head-on into another train on September 30.